Screw-pump.



R. BENNETT.

' SCREW PUMP. APPLICATION FILED IANA. |915.

1,211,390, i .y Patented .Ian.9?1917|.

ROBERT B. BENNETT, oFNEw YORK, N. Y., AssIGNoR To ERAsTUs s. BENNETT, oF NEW YORK, N. Y.

SCREW-PUMP.

Specication of Letters Patent.

Patented Jan. 9, 1917.

Continuation of application Serial No. 706,654, led .Tune 29, 1912. This application led January 4, 1916.

- Serial N o. 70,319.

To all whom 'it may concern:

Be it known that I, ROBERT B. BENNETT, a citizen ofthe United States, residing at 52 New street, New York city, New York, have invented certain new and useful Improvements in Screw-Pumps, of which the following is a specication. My invention relates particularly to the i mounting of the screw piston upon the shaft of the pump, my object being to avoid the use of keys or other forms of attachment,

which would in any way tend to weaken'the shaft or render necessary the existence of projections from the hub of the shaft into the working space within the cylinder of the pump. A pump of this character is in# tended to run at a very high speed, and as the screw piston is of considerable length a long shaft is usually. employed'. Further, such pumps are of small diameter but yet itis desirable to maintain a maximum working area within the pump cylinder. The clearance between the periphery of the screw piston and the inner wall of the cylinder must be exceedingly slight to prevent slip of the iuid, and the shaft must be perfectly straight .and no'irregularities or projections must occur on the screw piston or the hub 0r shaft `which would interfere with the perfect balance of the rotaryy piston and the proper working of the pump. With these 'considerations in mind it will be understood that the use of a. key for attaching the screw piston tothe hub. will not'meet the requirements, but is open to serious objection. The cutting of the keywaycauses springing of the shaft, and particularly in a shaft of the length required for .the best results in a screw pump of small diameter. A shaft that isslightly sprung, if used in a pump of this type, will cause the periphery of the screw piston to rub against the 'cylinder, causing friction at one. side and increasing the clearance hat the opposite side, and thus permitting slip of the uid. Further, a shaft when slightly sprung-in an apparatus of this character, because of the end pressurejto which the working parts arek subjected, tends constantly to lncrease its Iirregular form, correspondingly increasing the vibration and friction. Further, the forming of a key-seat in the shaft weakens it and necessitates the use of a shaft of larger diameter than would .be otherwise necessary, and this, in turn, requires a larger diameter of the hub' of the screw plston, and, correspondingly reduces the working area within the cylinder. The use of projections, set screws, bosses and the likeare objectionable, ,as the screw piston will be thrown out of balance and cause vibra-- tion, besides causing4 friction on the fluid and loss of efficiency inthe pump.

In carrying out my invention I seek toA avoid all of the above objections,I andthe inventlon consists in employing a screw piston of sectional form, each section comprising a hub and a screw blade, the differ-l ent hubs being interlocked one with the other and mounted upon a shaft, which is of plain cylindricaloform throughout its extentv cylinder, the connection l -between the sha t and the screw piston be within the "pum sc rew piston being shown in the elevation.

Flg. 2 is a section on line 2 2` of Fig. 1. Fig. 3 is a detail view of one of the screw piston sections, this being a central sectional view. Fig. 4 is a view of one of the diay phragms.

In these drawings, 1, indicates the'cylinder4 `of the pump made up of sections, and 2, in-

dicates diaphragme held between the sections and 'dividing the cylinder into chambers or spaces in which the sections 3, of the screw piston rotate. These diaphragms have openings 4 for the passage'of the water.-

The sections of the screw piston are made up of a hub 5, and a blade `6, of lscrew form, the hub being in tubular form, or in the form of a sleeve, having at one. end a pair of projections 7, extending from its rim and forming continuations of the cylindrical shell and at the other end,the hub is formed with1 notches 8, which are provided by cutting away the shell of the hub. The Iprojection 7 on one hub iits into the notch on the adjacent hub and there may be anydesired number of these projections and notches or recesses, two being employed in the present case. The interior diameter of the hub is the same as the diameter ofthe shaft 9,

which shaft extends through the casing or cylinder of the pump from end to end and rests in suitable bearings outside of the cylinder or casing. This shaft is connected vwith the screw piston by a sleeve which is pinned or otherwise secured to the shaft as at 11, the sleeve being located at the end of the screw piston and preferably -in the suction head or chamber 12 of the pump, which pump is providedby a curved coupling member or head 13. The sleeve is provided with projections, one of which, is shown at 14, forming'an extension'of the shell of the sleeve, and in the same curved plane from section to section of the screw piston through the interlocked hubs of said sections. The interlocked ends of the hubs lie within the central ring or bearing of the diaphragm 2. It will be seen from this construction that the shaft is left intact throughout, except where the sleeve 10 is attached thereto, no key seat being necessary, and as the shaft has its full strength and is not subjected to any action tending to spring it,

a shaft of small diameter may be used, and

vla piston hub of the minimum diameter may be employed, and thus a maximum working space will be provided'in which the screw piston may work. It will be also noticed that there are no projections, set screws, pins or other devices employed for fixing the hubs of the piston sections to the shaft, and thus the balance of the piston may be preserved and no obstructions of the flow of the fluid will exist. Because of dispensing with such fastening devices as a key, a screw, pm or the like, the shell of the piston hubs may be kept down to a minimum thickness to keep the diameter of the pumpv down to a minimum.

It will be observed that the sectional character of the pump is carried out with regard to the cylinder and also the piston, enabling any section to be removed, and this is true also as to.. the diaphragms"between which the sections of the piston Work. At the other end of the pump from the chamber 12 there is another chamber 17, formed by a curved shell 18.

I claim as my invention 1. In combination in a screw pump, a cylinder, a sectional screw piston having hubs interlocking, a shaft extending through said hubs and diaphragms within the cylinder surrounding the interlocking ends of the hubs, substantially as described.

1 2. Tn combination in a screw pump, a cylinder made up of sections, a screw piston made up of sections with interlocking hubs, a shaft-extending through the hubs and diaphragms held between the sections of the cylinderand surrounding the interlocking ends of the hubs, substantially as described.

In testimony whereof, I affix my signature in presence of two witnesses.

i; ROBERT B. BENNETT. l/Vitnesses:

MARY B. BENETT, C. B. WILKES. 

